/**
 *    Copyright (C) 2019-present MongoDB, Inc.
 *
 *    This program is free software: you can redistribute it and/or modify
 *    it under the terms of the Server Side Public License, version 1,
 *    as published by MongoDB, Inc.
 *
 *    This program is distributed in the hope that it will be useful,
 *    but WITHOUT ANY WARRANTY; without even the implied warranty of
 *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *    Server Side Public License for more details.
 *
 *    You should have received a copy of the Server Side Public License
 *    along with this program. If not, see
 *    <http://www.mongodb.com/licensing/server-side-public-license>.
 *
 *    As a special exception, the copyright holders give permission to link the
 *    code of portions of this program with the OpenSSL library under certain
 *    conditions as described in each individual source file and distribute
 *    linked combinations including the program with the OpenSSL library. You
 *    must comply with the Server Side Public License in all respects for
 *    all of the code used other than as permitted herein. If you modify file(s)
 *    with this exception, you may extend this exception to your version of the
 *    file(s), but you are not obligated to do so. If you do not wish to do so,
 *    delete this exception statement from your version. If you delete this
 *    exception statement from all source files in the program, then also delete
 *    it in the license file.
 */


#include "mongo/platform/basic.h"

#include <memory>
#include <openssl/rand.h>
#include <set>

#include "mongo/base/data_cursor.h"
#include "mongo/base/init.h"
#include "mongo/base/status.h"
#include "mongo/crypto/symmetric_crypto.h"
#include "mongo/crypto/symmetric_key.h"
#include "mongo/platform/random.h"
#include "mongo/util/assert_util.h"
#include "mongo/util/net/ssl_manager.h"
#include "mongo/util/str.h"

#define MONGO_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kStorage


namespace mongo {
namespace crypto {

namespace {
template <typename Init>
void initCipherContext(
    EVP_CIPHER_CTX* ctx, const SymmetricKey& key, aesMode mode, ConstDataRange iv, Init init) {
    const auto keySize = key.getKeySize();
    const EVP_CIPHER* cipher = nullptr;
    if (keySize == sym256KeySize) {
        if (mode == crypto::aesMode::cbc) {
            cipher = EVP_get_cipherbyname("aes-256-cbc");
        } else if (mode == crypto::aesMode::gcm) {
            cipher = EVP_get_cipherbyname("aes-256-gcm");
        } else if (mode == crypto::aesMode::ctr) {
            cipher = EVP_get_cipherbyname("aes-256-ctr");
        }
    }
    uassert(ErrorCodes::BadValue,
            str::stream() << "Unrecognized AES key size/cipher mode. Size: " << keySize
                          << " Mode: " << getStringFromCipherMode(mode),
            cipher);

    const bool initOk = (1 == init(ctx, cipher, nullptr, key.getKey(), iv.data<std::uint8_t>()));
    uassert(ErrorCodes::UnknownError,
            str::stream() << SSLManagerInterface::getSSLErrorMessage(ERR_get_error()),
            initOk);
}

class SymmetricEncryptorOpenSSL : public SymmetricEncryptor {
public:
    SymmetricEncryptorOpenSSL(const SymmetricKey& key, aesMode mode, ConstDataRange iv)
        : _ctx(EVP_CIPHER_CTX_new(), EVP_CIPHER_CTX_free), _mode(mode) {
        initCipherContext(_ctx.get(), key, mode, iv, EVP_EncryptInit_ex);
    }

    StatusWith<std::size_t> update(ConstDataRange in, DataRange out) final {
        int len = 0;
        if (1 !=
            EVP_EncryptUpdate(
                _ctx.get(), out.data<std::uint8_t>(), &len, in.data<std::uint8_t>(), in.length())) {
            return Status(ErrorCodes::UnknownError,
                          str::stream()
                              << SSLManagerInterface::getSSLErrorMessage(ERR_get_error()));
        }
        return static_cast<size_t>(len);
    }

    Status addAuthenticatedData(ConstDataRange in) final {
        fassert(51126, _mode == crypto::aesMode::gcm);

        auto swUpdate = update(in, {nullptr, 0});
        if (!swUpdate.isOK()) {
            return swUpdate.getStatus();
        }

        const auto len = swUpdate.getValue();
        if (len != in.length()) {
            return {ErrorCodes::InternalError,
                    str::stream() << "Unexpected write length while appending AAD: "
                                  << static_cast<int>(len)};
        }

        return Status::OK();
    }

    StatusWith<std::size_t> finalize(DataRange out) final {
        int len = 0;
        if (1 != EVP_EncryptFinal_ex(_ctx.get(), out.data<std::uint8_t>(), &len)) {
            return Status(ErrorCodes::UnknownError,
                          str::stream()
                              << SSLManagerInterface::getSSLErrorMessage(ERR_get_error()));
        }
        return static_cast<size_t>(len);
    }

    StatusWith<std::size_t> finalizeTag(DataRange out) final {
        if (_mode == aesMode::gcm) {
#ifdef EVP_CTRL_GCM_GET_TAG
            if (1 !=
                EVP_CIPHER_CTX_ctrl(
                    _ctx.get(), EVP_CTRL_GCM_GET_TAG, out.length(), out.data<std::uint8_t>())) {
                return Status(ErrorCodes::UnknownError,
                              str::stream()
                                  << SSLManagerInterface::getSSLErrorMessage(ERR_get_error()));
            }
            return crypto::aesGCMTagSize;
#else
            return Status(ErrorCodes::UnsupportedFormat, "GCM support is not available");
#endif
        }

        // Otherwise, not a tagged cipher mode, write nothing.
        return 0;
    }

private:
    std::unique_ptr<EVP_CIPHER_CTX, decltype(&EVP_CIPHER_CTX_free)> _ctx;
    const aesMode _mode;
};

class SymmetricDecryptorOpenSSL : public SymmetricDecryptor {
public:
    SymmetricDecryptorOpenSSL(const SymmetricKey& key, aesMode mode, ConstDataRange iv)
        : _ctx(EVP_CIPHER_CTX_new(), EVP_CIPHER_CTX_free), _mode(mode) {
        initCipherContext(_ctx.get(), key, mode, iv, EVP_DecryptInit_ex);
    }

    StatusWith<std::size_t> update(ConstDataRange in, DataRange out) final {
        int len = 0;
        if (1 !=
            EVP_DecryptUpdate(
                _ctx.get(), out.data<std::uint8_t>(), &len, in.data<std::uint8_t>(), in.length())) {
            return Status(ErrorCodes::UnknownError,
                          str::stream()
                              << SSLManagerInterface::getSSLErrorMessage(ERR_get_error()));
        }
        return static_cast<std::size_t>(len);
    }

    Status addAuthenticatedData(ConstDataRange authData) final {
        fassert(51125, _mode == crypto::aesMode::gcm);

        auto swUpdate = update(authData, {nullptr, 0});
        if (!swUpdate.isOK()) {
            return swUpdate.getStatus();
        }

        const auto len = swUpdate.getValue();
        if (len != authData.length()) {
            return {ErrorCodes::InternalError,
                    str::stream() << "Unexpected write length while appending AAD: "
                                  << static_cast<int>(len)};
        }

        return Status::OK();
    }

    StatusWith<std::size_t> finalize(DataRange out) final {
        int len = 0;
        if (1 != EVP_DecryptFinal_ex(_ctx.get(), out.data<std::uint8_t>(), &len)) {
            return Status(ErrorCodes::UnknownError,
                          str::stream()
                              << SSLManagerInterface::getSSLErrorMessage(ERR_get_error()));
        }
        return static_cast<std::size_t>(len);
    }

    Status updateTag(ConstDataRange tag) final {
        // validateEncryptionOption asserts that platforms without GCM will never start in GCM mode
        if (_mode == aesMode::gcm) {
#ifdef EVP_CTRL_GCM_GET_TAG
            if (1 !=
                EVP_CIPHER_CTX_ctrl(_ctx.get(),
                                    EVP_CTRL_GCM_SET_TAG,
                                    tag.length(),
                                    const_cast<std::uint8_t*>(tag.data<std::uint8_t>()))) {
                return Status(ErrorCodes::UnknownError,
                              str::stream()
                                  << "Unable to set GCM tag: "
                                  << SSLManagerInterface::getSSLErrorMessage(ERR_get_error()));
            }
#else
            return {ErrorCodes::UnsupportedFormat, "GCM support is not available"};
#endif
        } else if (tag.length() != 0) {
            return {ErrorCodes::BadValue, "Unexpected tag for non-gcm cipher"};
        }

        return Status::OK();
    }

private:
    std::unique_ptr<EVP_CIPHER_CTX, decltype(&EVP_CIPHER_CTX_free)> _ctx;
    const aesMode _mode;
};

}  // namespace

std::set<std::string> getSupportedSymmetricAlgorithms() {
#if defined(EVP_CTRL_GCM_GET_TAG) && !defined(__APPLE__)
    return {aes256CBCName, aes256GCMName, aes256CTRName};
#else
    return {aes256CBCName, aes256CTRName};
#endif
}

Status engineRandBytes(DataRange buffer) {
    if (RAND_bytes(buffer.data<std::uint8_t>(), buffer.length()) == 1) {
        return Status::OK();
    }
    return {ErrorCodes::UnknownError,
            str::stream() << "Unable to acquire random bytes from OpenSSL: "
                          << SSLManagerInterface::getSSLErrorMessage(ERR_get_error())};
}

StatusWith<std::unique_ptr<SymmetricEncryptor>> SymmetricEncryptor::create(const SymmetricKey& key,
                                                                           aesMode mode,
                                                                           ConstDataRange iv) try {
    std::unique_ptr<SymmetricEncryptor> encryptor =
        std::make_unique<SymmetricEncryptorOpenSSL>(key, mode, iv);
    return std::move(encryptor);
} catch (const DBException& e) {
    return e.toStatus();
}

StatusWith<std::unique_ptr<SymmetricDecryptor>> SymmetricDecryptor::create(const SymmetricKey& key,
                                                                           aesMode mode,
                                                                           ConstDataRange iv) try {
    std::unique_ptr<SymmetricDecryptor> decryptor =
        std::make_unique<SymmetricDecryptorOpenSSL>(key, mode, iv);
    return std::move(decryptor);
} catch (const DBException& e) {
    return e.toStatus();
}

}  // namespace crypto
}  // namespace mongo